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Message-ID: <Pine.LNX.4.44L0.1611101035140.1667-100000@iolanthe.rowland.org>
Date: Thu, 10 Nov 2016 10:36:18 -0500 (EST)
From: Alan Stern <stern@...land.harvard.edu>
To: Kai-Heng Feng <kai.heng.feng@...onical.com>
cc: Bjørn Mork <bjorn@...k.no>,
Oliver Neukum <oneukum@...e.com>,
<linux-kernel@...r.kernel.org>, <linux-usb@...r.kernel.org>,
<netdev@...r.kernel.org>
Subject: Re: [PATCH] usbnet: prevent device rpm suspend in usbnet_probe
function
On Thu, 10 Nov 2016, Kai-Heng Feng wrote:
> Hi,
>
> On Wed, Nov 9, 2016 at 8:32 PM, Bjørn Mork <bjorn@...k.no> wrote:
> > Oliver Neukum <oneukum@...e.com> writes:
> >
> >> On Tue, 2016-11-08 at 13:44 -0500, Alan Stern wrote:
> >>
> >>> These problems could very well be caused by running at SuperSpeed
> >>> (USB-3) instead of high speed (USB-2).
>
> Yes, it's running at SuperSpeed, on a Kabylake laptop.
>
> It does not have this issue on a Broadwell laptop, also running at SuperSpeed.
>
> >>>
> >>> Is there any way to test what happens when the device is attached to
> >>> the computer by a USB-2 cable? That would prevent it from operating at
> >>> SuperSpeed.
>
> I recall old Intel PCH can change the USB host from XHCI to EHCI,
> newer PCH does not have this option.
>
> Is there a way to force XHCI run at HighSpeed?
Yes, like I said above: Use a USB-2 cable instead of a USB-3 cable.
Alan Stern
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